U.S. Pat. Nos. 4,842,464, 4,956,888 and 5,086,532 disclose a novel type of nut having a thread of varying pitch which acts to distribute the axial load applied to the nut more uniformly between the different turns of the thread than is possible with a conventional thread whose pitch does not vary. These patents show methods and apparatus for manufacturing such nuts by employment of lathe type threading tools having a single point which takes a series of cuts in the work piece, or a similar tool having two projections for simultaneously forming opposite side surfaces of the thread. U.S. Pat. No. 5,250,007 shows another method of forming a thread of varying pitch, utilizing a threading assembly consisting of several thread forming elements which rotate and advance axially relative to the work piece essentially in unison, and which also shift axially relative to one another during a threading operation in a manner producing together the desired thread of varying pitch.